Edible Tropicals

Tuesday, September 20, 2016

Coffee is ubiquitous in most of the world, with potentially a billion people around the world drinking it on a daily basis. Dark, roasted beans are ground and brewed to produce an energetic, caffeine infused drink that is relied on by most for a productive day at work. Though, if you ask someone where their coffee comes from, they might say the grocery store, and if they are an informed shopper, they might even say the country in which their coffee was grown. However, few in temperate-climate areas stop to think about where their coffee comes from and how it was prepared.

Coffea arabica is the predominant species of Coffea cultivated for consumption, although many other species exist, some of which are also consumed in a similar fashion. This tropical shrub is well suited to tropical climates, and is an important cash crop in many countries. Additionally, Coffea arabica is well suited to controlled environment cultivation and will readily set fruit in greenhouses, and even indoors as houseplants. If you're lucky enough to have a mature, fruiting coffee tree, you will be able to make use of the fruits to brew your own coffee, completely from scratch!

The fruits of a coffee tree are called coffee cherries, and when ripe, turn a dark red color and acquire a sweet flavor with a gentle tartness. These cherries are in fact edible, and in my opinion at least, taste pretty good. The outer skin and thin layer of flesh make for a tasty treat, but be careful not to bite into the hard coffee beans inside. Although coffee cherries can be eaten, the real prize are the beans within. To begin the process of preparing one's own coffee, they will have to sacrifice the fruits. The skin and flesh of the coffee cherries will be valuable in the process of fermentation in the wet processing method commonly used in coffee preparation. The dry method may also be used, although this entails leaving the entire fruits to dry, becoming prone to mold, which can be a problem in home preparation.

Homemade coffee via the wet process method:

Step 1: Collecting and washing fruits

Coffee cherries are ripe and ready for harvest when they turn a deep red color, but are still plump and relatively firm to the touch. Coffee cherries that are green or dark and shriveled up should be avoided! Understandably, you might have to collect some light red cherries as well in order to have a harvest large enough to make any meaningful amount of coffee. Furthermore, unless you have access to many fruiting coffee trees, this whole task can be difficult as not all fruits ripen at the same time. Once ripe fruits are collected the next step, fermentation, should be started as soon as possible, definitely within the same day of harvest.

Step 2: Fermentation

Each coffee cherry contains two coffee beans (or in the case of the occasional "peaberry", only a single bean is present in a cherry). These coffee beans are surrounded by a thin but slimy layer of mucilage that must be removed prior to the next step to ensure that the beans may be properly dried. The wet process method uses a fermentation step to help break down the mucilaginous layer surrounding each coffee bean. To begin this process, fresh fruit should be squeezed to eject the inner beans, and both the beans and fruit skins should be placed in a large bowl. Water should be added to the bowl, about 3 parts water per 1 part of coffee fruit should be a good ratio to ensure proper fermentation. Too much water may inhibit fermentation by diluting the enzymes too much. The skins and floating beans that rise to the surface of the mixture should be removed. The beans should be mixed occasionally with a non-metal spoon. Fermentation will be complete in as soon as 12 hours but may take as long as 48 hours. This process is complete when the beans have a rough texture that predominates the slimy texture, indicating that the mucilage has been adequately degraded.

Notably, fermentation does not always occur readily when attempting the wet process at home. If after 36-48 hours, the beans are still slimy, physical abrasion will be required to fully remove the mucilage. This can be done by rubbing the beans between a towel or exposing them to some other kind of abrasion.

Finally, all remaining pieces of fruit flesh should be removed from the mixture and the beans should be washed several times with fresh water and strained to remove any remaining pieces of fruit.

Step 3: Drying

Beans should be left out to dry, preferably in the sun for 5-15 days. It is also possible to dry the seeds on a cookie tray left out by a window sill. When the beans are fully dry, the parchment surrounding the seed becomes brittle and will break off with ease. The bean inside the parchment must also be dry enough to crack easily when crushed. I like to bite off the end of a bean as a test - if the beans are soft, they are not ready but if they crack easily when bitten then they should be dry enough.

Step 4: De-hulling

Once the beans are dry, the parchment (or hull) needs to be removed from each bean. While there are several high-throughput ways to do this, I do it by hand. I pull apart the hull along the seam on the flat side of the bean using my finger nail. This is a very time consuming process, so alternatively, a rolling pin may be used to gently break apart the hulls (though, be careful not to break the beans in doing so).

Step 5: Roasting

This is arguably the most important step in preparing coffee. While commercial coffee roasters have access to specialized equipment that provides ideal conditions for coffee roasting, home roasters have less desirable options. Some people opt to roast beans in a popcorn popper, but I have heard that this often burns the beans and can even ruin your popcorn machine.

I would argue that roasting beans in an oven or on a skillet would be the best options for a home roaster. Either of these methods will work fine, but both likely have trade offs in terms of flavor and roast consistency. Occasionally stirring the beans is very important to ensure an even roast, and the higher the temperature the more often beans should be stirred to prevent burning. It should take about 15 minutes to complete the roasting process at ~240°F, although I have found this to vary dramatically based on roasting temperature. It's possible to roast at slightly lower temperatures (~220°F) for longer to ensure that you don't over-roast. The most important thing is to watch the color of the beans. You may be looking for either a light, medium, or dark roast, so you should pay close attention to the color of the beans during the roasting process to ensure you don't under or over shoot your goal. Beans will initially change to a yellow-ish color, grading into a gold, then brown. A final consideration is that the beans will still hold a lot of heat and will continue to cook for a couple of minutes after roasting. A fan can be used to combat this if you're afraid of over roasting.

Wednesday, October 14, 2015

Black pepper (Piper nigrum) is a common spice with a rich history. Peppercorns from black pepper have been traded for thousands of years and the peppercorn trade is still very much alive and well today. This highly sought after spice owes its fame to an alkaloid called piperine which gives pepper its spiciness. However, P. nigrum isn't the only species of pepper, actually there are at least one thousand Piper species many of them containing piperine and/or other unique compounds, some are even known stimulants. Some interesting species include Betel (P. betle), Cubeb (P. cubeba), West African Pepper (P. guineense), Long Pepper (P. longum) and Kava (P. methysticum). Not all Piper species are prized for their fruits, or peppercorns, others have highly sought after leaves. One such example is lolot (P. lolot), which is a component of thịt bò nướng lá lốt, a Vietnamese cuisine which consists of beef wrapped in lolot leaves and grilled.

I will focus on propagation methods for only two species, black pepper (P. nigrum) and lolot (P. lolot), although these methods will likely be effective with other species of Piper as well.

Growing black pepper by seed:
Soak in water for 24 hours (or more) until the seeds are visibly hydrated and plump.
Plant the seeds about 1/4th inch in moist potting soil and keep the soil moist. Germination typically occurs within one month.

Propagating lolot:
I don't know of any examples of growing lolot by seed, although this may be possible. As with many species of Piper, the preferred method of propagation for lolot is by rooting. This method is of course impossible without having a parent plant, however they are available for sale as live plants from some internet vendors as well as from some tropical plant nurseries in the U.S. The following vegetative propagation methods for lolot will also apply for black pepper.

Rooting lolot is easy, simply place a stem under some soil, preferably one that is already growing low to the ground. Burying a horizontal stem, or "runner", encourages root formation and once the roots are well established you may sever the stem from the parent plant. This effectively creates a clone that can be re-potted. I have found that lolot does very well in my greenhouse, and has grown from a small plant taken from a cutting into a large three foot tall bush in only six months. It often sends out runner stems which grow along my greenhouse floor and snake between plant pots sending roots into the ground as it goes. These are easy to pull up, cut into segments and re-pot as new lolot plants.

Propagating less vigorous lolot plants can easily be done by rooting cuttings or air-layering. Rooting cuttings is easy, but often proves to be a less successful technique of cloning from a parent plant. Simply find an older stem that is strong and firm, remove the leaf from the first node up, dip the cutting in a rooting hormone and place it in a new pot. The soil should be well draining and aerated, ideally containing a lot of vermiculite. Keep the soil moist as the cutting begins to develop roots.

Monday, October 13, 2014

Dragonfruit, aka pitaya, is often cultivated by cuttings but may also be grown from seeds. Propagation from seeds is by far the easiest method to attempt, however success is sometimes hard to come by. Dragonfruits are filled with tons of small black seeds that are edible, just as those in a kiwi, and germinate readily from fresh fruit. It should be noted that taking good care of dragonfruit seedlings proves to be a challenging endeavor without the correct environment.

Growing Dragonfruit from seed:
Firstly you must obtain a dragonfruit, cut it open, and begin to harvest the minuscule seeds. Try carefully to collect only the seeds and not the surrounding flesh. Then, if possible, you should rinse the seeds and clean them of the sugary flesh and juice that has the potential to lead to rotting and disease during the germination process. I use a metal tea strainer to do this, rinsing several times while removing any visible pieces of flesh.

For maximum germination rates, spread the cleaned seeds evenly across a moist paper towel, fold and place it in a bag and keep them in a warm spot for a few weeks. Once roots begin to emerge, you may transplant the seedlings into soil pots filled with a typical cacti soil mix or one with a mix of vermiculite, perlite and peat moss. Alternatively, cleaned seeds may be sowed directly in a potting mix (at a shallow depth of ~ 1/16in.), however often with decreased success.

Once germinated, seedlings will send out relatively long white roots, at which point they should be transplanted. If allowed to grow too long, the roots will become entangled in the paper towel and damage will be inevitable. The seeds require somewhat bright light during the day, this can be provided by a full spectrum lamp or from sunlight coming through a window. A humidome or plastic covering will keep in crucial humidity while still allowing the soil to dry out slightly. If grown outside in full sun, the seedlings will benefit from a little bit of shade and protection from the elements.

The most tricky part of growing dragonfruit from seed is getting passed the cotyledon stage of growth. The seedlings are very small and delicate, especially prone to root rot. Be careful not to water too much, and if you notice seedlings dying with shriveled brown roots you need to start watering less - this may also be an indication of poorly draining or compacted soil.

Sunday, September 7, 2014

Sapindaceae is a large plant family that includes many common and economically important genera and species, including maple trees, rambutan, longan and lychee. Lychee fruit comes from the Litchi chinensis tree and is in the monotypic genus Litchi, meaning it is the only species in the genus. Despite this, it is very similar in appearance to its relatives, the rambutan and longan. The lychee comes from China where it is a well-liked fruit and for the most part commercial cultivation is limited to south east Asia. The lychee tree can grow quite tall, and yields large bunches of bright (reddish) colored fruits.

Lychee trees can be grown in tropical and sub-tropical climates, requiring warm and wet summers as well as mild winters. Although they can handle short periods of frost, they are rather sensitive. Despite this they have been cultivated in many parts of the world including in the lower states of the U.S.

Lychee fruit can be purchased easily during the correct season (May - July) and often at a reasonable price. The fruits have three main components, a thin tough rind, thick sugary flesh and a hard dark seed. The flesh is delicious fresh, it is juicy with a somewhat floral flavor, and is stored well in the freezer for later use.

Growing lychee from seed:Lychee seeds are quite easy to germinate through a variety of methods. Choose seeds that are from freshly eaten fruit, as they will have a much higher germination rate. Be sure to clean off any excess fruit from the seeds.

Firstly, the seeds should be soaked in water for about three days, each day the water should be changed. You will notice that the dark shell of the seed will begin to split, this is when you may begin the next step of germination. I have tested germination directly in soil and using a wet paper towel in a plastic bag and they are both comparable. So follow the method that is easiest for you. The seeds should be planted in well draining potting soil, ideally one with vermiculite and perlite, but most commercial potting soils will do just fine. Plant at a depth of about 3/4 inches.

Lychee seedlings may be grown inside near a window that receives a lot of natural light, or alternatively they can be planted in pots and kept outside until winter. Of course, lychees will do much better in sub-tropical and tropical climates, they can also be brought to flower and fruit in greenhouses.

Avoid fertilizing lychee seedlings for the first year, and only light applications until growth becomes large and woody.

Upon germinating, the lychee seed will provide the necessary nutrients to support the growth of a main root and shoot. As the shoot emerges from the soil the cotyledons will begin to develop. Initially the leaves will be slightly discolored, often yellow or purplish, but as the leaves begin to generate chlorophyll the leaves will turn a dark green. At this point the seedling is capable of conducting photosynthesis and true leaf growth will begin.

Sunday, August 17, 2014

Phoenix is a genus in the family Arecaceae which is composed of about a dozen species. The most economically important of which is Phoenix dactylifera, the true date palm. Fruits of the date palm contain very high sugar content and are prized for the energy they provide.

Date palms generally require very warm and sunny summers with mild winters, typical of many regions of the Middle East. Dates are commercially cultivated in the Middle East, parts of Africa, many islands and subtropical locations, but also in the United States. Dates are cultivated commercially in many states including California and Arizona. In order to ensure successful harvests, dates must be grown in arid regions that have hot summer temperatures and only mild freezes in the winter months. On top of that, fruit production requires a lot of water, despite the fact that dates can withstand long droughts.

Date trees are versatile, serving as much more than a shade tree that provides fruit. Sap can be tapped from the trees, which can then be used as a sweetening syrup or fermented into an alcoholic drink. The leaves are used for a variety of purposes such as roofing for houses, and crafts such as baskets. Seeds can even be used as a feed-stock for animals.

There are over one hundred cultivars of dates grown around the world and the differences between them can be quite stark. For instance, the Deglet Noor date is generally light in color with firm flesh where as Medjool dates have a dark color with thick and soft flesh. Some dates are small, some large, while others are moist with sugars and syrup others can be dry to the touch. Quite possibly my favorite dates are the Jumbo Medjool dates which are especially large compared to typical Medjool or Deglet Noor dates.

Growing date palms from seed:

This method is quite easy but actually yielding fruit from your trees will be a bit more challenging. To grow a date palm simply eat a date, remove the seed and wash it clean of any excess flesh.

Next soak the seeds in water for at least 24 hours (or 48 hours), which will allow the strong seed coat of the date seeds to imbibe water.

There are many methods for germinating date seeds, but there are two easy methods for most date seeds. The first is to sow the date seed (rough side down) about 1" into a small pot filled with soil. Lightly water the soil occasionally ensuring moisture at the seed's depth, while being careful not to over-water the soil.

The second method is to wrap the date seeds in a slightly moist paper towel and put them in a plastic bag. Place the bagged seeds in a warm place, at least 75°F and small white roots will begin to appear from one side of the date seeds. The germinated seeds may then be planted in a small or medium sized pot filled with a palm or cactus potting soil.

Date seeds are really picky when it comes to moisture, they want to be only slightly moist so be sure not to over water the seeds. Other germination methods work better for tricky seeds, and these include the incorporation of sand and vermiculite to help regulate the moisture of the soil.

Potting soil for date palms:
Palm or cactus potting soil mixes are a good choice for planting date palms in, and they are usually available at home and garden stores. Alternatively you may add sand and/or vermiculite to a generic potting soil (in a 1:4 or 1:3 ratio) to provide good aeration and drainage. Adding peat moss to the soil will help the soil retain moisture if it is draining too well. Most palm or cactus potting soils have a good mixture of sand, vermiculite, perlite and peat moss and will be the most suitable for date palms.

Once you have a date palm seedling established, you must cater to its growth by transplanting it gradually to larger and larger pots. Transplant your date palm when you notice that it is outgrowing its container or growing roots out from under the container. Be sure to water the palm well before and after transplanting and avoid transplanting into a significantly larger pot. Alternatively the palm may be transplanted into the ground if your climate supports its growth. Otherwise date palms may be kept in large pots outdoors, on a porch or somewhere receiving maximum sunlight. It may be possible to keep date palms indoors near a window that receives direct sunlight, although its growth will likely be severely hindered.

Date palms are dioecious, meaning that each plant is either male or female. Females are more desired because they will bear fruit, while the males only provide the pollen to fertilize the females. This means that only one male plant is needed to pollinate many females. The pollen grains of date palms are small and can easily travel by wind to pollinate the females, but commercially it is hand pollination that is the method of choice to ensure maximum fertilization.

Growing date palms by seeds results in plants that are not true-to-type, meaning the seedlings will develop into palms with fruits that may be smaller and of lesser quality than the parent. On top of this, only about half of the seeds that germinate will be the desired females. Therefore vegetative propagation is the preferred method of many commercial farms and nurseries. This can be done through tissue culture in a laboratory setting or by offshoot rooting of young date palms.

Date palm propagation by offshoots:
Young date palms, about ten years of age, will begin to send offshoots from the basal portions of the trunk. These offshoots are directly connected to the parent plant, and thus receive all of their nutrients and water from the parent. Overtime they will develop roots that will bury into the soil to support their independent growth. This may be facilitated by building soil up around the offshoot if it appears close to the parent trunk. Over time these may be severed from the parent plant and potted in a process that should only be done by experts to ensure success. Although this is a long and time consuming method of propagation, it results in true-to-type clones of a female plant that will have a head start over date palms started by seed.

Above are ripe fruits of the Silver Date Palm (Phoenix sylvestris) which is a date palm with a sweet sap that is used to make palm wine. The fruits are edible but have only a small layer of flesh, though I find them to be delicious.

This is an inexpensive box of Iranian dates the cultivar of which I do not know. There is a huge difference between these low quality dates and those that fetch over a fifty dollars a kilogram. I found these dates to have a soggy texture and a thick outer skin.

Green, firm immature fruits can be seen on this date palm (Phoenix dactylifera)
A closeup of this date palm (Phoenix dactylifera) shows mature offshoots that were allowed to grow, and the many small knobs from offshoots that were cut back long ago. Notice the roots that emerged from the old offshoots.